SQLite

*************************************************************************
**
** Memory allocation functions used throughout sqlite.
*/
#include "sqliteInt.h"
#include <stdarg.h>









































/*
** Attempt to release up to n bytes of non-essential memory currently
** held by SQLite. An example of non-essential memory is memory used to
** cache database pages that are not currently in use.
*/
int sqlite3_release_memory(int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT

  ** True if heap is nearly "full" where "full" is defined by the
  ** sqlite3_soft_heap_limit() setting.
  */
  int nearlyFull;
} mem0 = { 0, 0, 0, 0, 0, 0, 0 };

#define mem0 GLOBAL(struct Mem0Global, mem0)

/*
** This routine runs when the memory allocator sees that the
** total memory allocation is about to exceed the soft heap
** limit.
*/
static void softHeapLimitEnforcer(
  void *NotUsed, 
  sqlite3_int64 NotUsed2,
  int allocSize
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  sqlite3_release_memory(allocSize);
}

/*
** Change the alarm callback
*/
static int sqlite3MemoryAlarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  int nUsed;
  sqlite3_mutex_enter(mem0.mutex);
  mem0.alarmCallback = xCallback;
  mem0.alarmArg = pArg;
  mem0.alarmThreshold = iThreshold;
  nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
  mem0.nearlyFull = (iThreshold>0 && iThreshold<=nUsed);
  sqlite3_mutex_leave(mem0.mutex);
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_DEPRECATED
/*
** Deprecated external interface.  Internal/core SQLite code
** should call sqlite3MemoryAlarm.
*/
int sqlite3_memory_alarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  return sqlite3MemoryAlarm(xCallback, pArg, iThreshold);
}
#endif

/*
** Set the soft heap-size limit for the library. Passing a zero or 
** negative value indicates no limit.
*/
sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
  sqlite3_int64 priorLimit;
  sqlite3_int64 excess;
#ifndef SQLITE_OMIT_AUTOINIT
  sqlite3_initialize();
#endif
  sqlite3_mutex_enter(mem0.mutex);
  priorLimit = mem0.alarmThreshold;
  sqlite3_mutex_leave(mem0.mutex);
  if( n<0 ) return priorLimit;
  if( n>0 ){
    sqlite3MemoryAlarm(softHeapLimitEnforcer, 0, n);
  }else{
    sqlite3MemoryAlarm(0, 0, 0);
  }
  excess = sqlite3_memory_used() - n;
  if( excess>0 ) sqlite3_release_memory(excess & 0x7fffffff);
  return priorLimit;
}
void sqlite3_soft_heap_limit(int n){
  if( n<0 ) n = 0;
  sqlite3_soft_heap_limit64(n);
}

/*
** Initialize the memory allocation subsystem.
*/
int sqlite3MallocInit(void){
  if( sqlite3GlobalConfig.m.xMalloc==0 ){
    sqlite3MemSetDefault();

  int n, mx;
  sqlite3_int64 res;
  sqlite3_status(SQLITE_STATUS_MEMORY_USED, &n, &mx, resetFlag);
  res = (sqlite3_int64)mx;  /* Work around bug in Borland C. Ticket #3216 */
  return res;
}


































/*
** Trigger the alarm 
*/
static void sqlite3MallocAlarm(int nByte){
  void (*xCallback)(void*,sqlite3_int64,int);
  sqlite3_int64 nowUsed;
  void *pArg;

** <dd> ^This option takes single argument of type int, interpreted as a 
** boolean, which enables or disables the collection of memory allocation 
** statistics. ^(When memory allocation statistics are disabled, the 
** following SQLite interfaces become non-operational:
**   <ul>
**   <li> [sqlite3_memory_used()]
**   <li> [sqlite3_memory_highwater()]
**   <li> [sqlite3_soft_heap_limit64()]
**   <li> [sqlite3_status()]
**   </ul>)^
** ^Memory allocation statistics are enabled by default unless SQLite is
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
**

  const char *zPassPhrase        /* Activation phrase */
);
#endif

/*
** CAPI3REF: Suspend Execution For A Short Time
**
** The sqlite3_sleep() function causes the current thread to suspend execution
** for at least a number of milliseconds specified in its parameter.
**
** If the operating system does not support sleep requests with
** millisecond time resolution, then the time will be rounded up to
** the nearest second. The number of milliseconds of sleep actually
** requested from the operating system is returned.
**
** ^SQLite implements this interface by calling the xSleep()
** method of the default [sqlite3_vfs] object.  If the xSleep() method
** of the default VFS is not implemented correctly, or not implemented at
** all, then the behavior of sqlite3_sleep() may deviate from the description
** in the previous paragraphs.
*/
int sqlite3_sleep(int);

/*
** CAPI3REF: Name Of The Folder Holding Temporary Files
**
** ^(If this global variable is made to point to a string which is

** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
*/
int sqlite3_release_memory(int);

/*
** CAPI3REF: Impose A Limit On Heap Size
**
** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
** soft limit on the amount of heap memory that may be allocated by SQLite.
** ^SQLite strives to keep heap memory utilization below the soft heap
** limit by reducing the number of pages held in the page cache
** as heap memory usages approaches the limit.
** ^The soft heap limit is "soft" because even though SQLite strives to stay
** below the limit, it will exceed the limit rather than generate
** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 

** is advisory only.
**
** ^The return value from sqlite3_soft_heap_limit64() is the size of

** the soft heap limit prior to the call.  ^If the argument N is negative
** then no change is made to the soft heap limit.  Hence, the current
** size of the soft heap limit can be determined by invoking
** sqlite3_soft_heap_limit64() with a negative argument.
**
** ^If the argument N is zero then the soft heap limit is disabled.
**
** ^(The soft heap limit is not enforced in the current implementation

** if one or more of following conditions are true:
**
** <ul>
** <li> The soft heap limit is set to zero.
** <li> Memory accounting is disabled using a combination of the
**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
** <li> An alternative page cache implementation is specifed using
**      [sqlite3_config]([SQLITE_CONFIG_PCACHE],...).
** <li> The page cache allocates from its own memory pool supplied
**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
**      from the heap.
** </ul>)^
**
** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
** the soft heap limit is enforced on every memory allocation.  Without
** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
** when memory is allocated by the page cache.  Testing suggests that because
** the page cache is the predominate memory user in SQLite, most
** applications will achieve adequate soft heap limit enforcement without
** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
**
** The circumstances under which SQLite will enforce the soft heap limit may
** changes in future releases of SQLite.
*/
sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);

/*
** CAPI3REF: Deprecated Soft Heap Limit Interface
** DEPRECATED
**
** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
** interface.  This routine is provided for historical compatibility


** only.  All new applications should use the


** [sqlite3_soft_heap_limit64()] interface rather than this one.
*/
SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);


/*
** CAPI3REF: Extract Metadata About A Column Of A Table
**
** ^This routine returns metadata about a specific column of a specific
** database table accessible using the [database connection] handle
** passed as the first function argument.

int sqlite3DbMallocSize(sqlite3*, void*);
void *sqlite3ScratchMalloc(int);
void sqlite3ScratchFree(void*);
void *sqlite3PageMalloc(int);
void sqlite3PageFree(void*);
void sqlite3MemSetDefault(void);
void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));

int sqlite3HeapNearlyFull(void);

/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**

*/
static int test_soft_heap_limit(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){

  sqlite3_int64 amt;
  sqlite3_int64 N = -1;
  if( objc!=1 && objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "?N?");
    return TCL_ERROR;
  }

  if( objc==2 ){

    if( Tcl_GetWideIntFromObj(interp, objv[1], &N) ) return TCL_ERROR;


  }
  amt = sqlite3_soft_heap_limit64(N);
  Tcl_SetObjResult(interp, Tcl_NewWideIntObj(amt));
  return TCL_OK;
}

/*
** Usage:   sqlite3_thread_cleanup
**
** Call the sqlite3_thread_cleanup API.